Pump control system



United States Patent PUlVIP CONTROL SYSTEM Maurice C. McCray and Warren Doble, North Hollywood, Califl, assignors to Jabsco Pump Company, Burbank, Califl, a corporation of California Application September 17, 1956, Serial No. 610,249

6 Claims. (Cl. 103-23) .'lhe present inventionrelates in general to pumps and, more, particularly, to control systems for pumps, a general object of the invention, being to provide a control system having means: for preventing operation of a pump controlled thereby when the fluid supply to the pump is interrupted.

Pumps; are: not infrequently utilized to maintain fluid levels below predetermined maximums, the pumps being operated periodically whenever the fluid levels approach such; maximums and normally being inoperative when the fluid levels are at or near acceptable minimums. Considering a typical example, a bilge pump is normally operated only when the water level in the bilge of a boat approaches a. predetermined. maximum and is normally inoperative when, the water level in the bilge is at or near a predetermined minimum value. Such an environment for the present invention is hereby elected for specific consideration; herein without limiting the. invention thereto.

Ordinarily; thebilge of aboat is pumped out at irregularxintervals', the operator energizing or activating the pump drive. means; whenever an excessive amount of water. collects: in the bilge. The bilge pump may, for example, be: placed in operation by energizing a clutch connecting the pump to the engine of the boat, 'the clutch normally being energized manually in small boats at. least. It has. been found; that, particularly in boats designed: for one-man. operation, the operator frequently neglects to deenergize the clutch, or other drive means, connected to the. pump after the bilge has been pumped dry, with the result that thepump may be operated for prolonged periods without any water flow therethrough. This condition frequently resultsin damage to the pump since. pumps: ordinarily rely on the fluid being pumped thereby. to perform. lubrication and cooling functions. In fact, when a bilge pump which is equipped with a rubber impeller, or an impeller of some other elastomeric material, is run dry for any length of time due to failure of the operator to d'eenergize the drive means therefor, the impeller burnsout for lack of water to lubricate and cool it. If such a pump is run dry long enough, the heat generated eventually elevates the temperature of the entire pump to such an extent that the lubricant is forced out of the bearings for the impeller shaft so that the bearings seize, thereby ruining the entire pump. Such pump damage is expensive to say the least and may, under some circumstances, result in serious danger to the safety of the person or persons abroad the boat.

A primaryobject of the present invention is to eliminatel any possibility of developments of the foregoing nature by providing a pump control system having means for automatically deenergizing the pump drive means upon interruption of fluid flow through the pump. Thus, in a bilge pump installation, the moment the bilge is pumped dry, the pump is stopped to prevent damage thereto, which is an important feature.

.MQre. specifically, an important object of the invention is. to provide a pump control. system having; meansresponsive to fluid flow into the inlet of the pump for maintaining the pump drive means energized, i.e., having means responsive to any interruption of fluid flow into the inlet for deenergizing the pump drive means. By making the energization cf the pump drive means responsive to the flow of fluid into the pump inlet in this manner, the operation of the pump is stopped as soon as the source of fluid is pumped dry. Consequently, the pump itself always contains fluid for lubrication and cooling purposes and can never operate without fluid therein, which is an important feature. Also, if the pump is of the type. which requires priming, no priming is necessary when the operation of the pump is terminated immediately upon interruption of fluid flow into the inlet in accordance with the invention.

Another object is to provide means responsive to a predetermined pressure in the pump inlet for maintaining the pump drive means energized. More specifically, an object is to provide diaphragm means responsive to a pressure less than atmospheric in the pump inlet for maintaining the pump drive means energized and for deenergizing the pump drive means whenever the pressure in the inlet approaches atmospheric due to pumping the bilge, or other source of fluid, dry.

Another object is to provide a pump drive means which includes a clutch comprising a continuously operating driving element and comprising a driven element connected to the pump, one of these elements being movable into and out of driving engagement with the other by the diaphragm means mentioned.

Another object is to provide a diaphragm means which includes a diaphragm responsive to a pressure less than atmospheric in the pump inlet for moving the movable clutch element into engagement with the other clutch element, and which includes spring means for moving the movable clutch element out of engagement with the other clutch element upon failure of the pump suction due to pumping the source dry.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results thereof whichwill be apparent to those skilled in the pump art in the light of this disclosure, may be attained with the exemplary embodiment of the invention described hereinafter and illustrated in the accompanying drawing, the latter being a semidiagrammatic viewof a pump control system of the invention with various components in section.

Referring to the drawing, the numeral 10 designates a boat the bilge 12 of which is designed to be pumped by a pump 1 This pump may be of any suitable type and may be provided with an elastomeric impeller 16. The pump 14 is provided with an inlet 18 and an outlet 29, the former including an inlet line 22 connected to an inlet port 24 of the pump and extending downwardly into the bilge l2, and the latter including an outlet line 23 connected to an outlet port 26 of the pump and extending to the exterior of the boat to discharge the water pumped from the bilge overboard.

The pump 14 includes a drive shaft 30 connected to the impeller 16, the invention providing drive means 32 driving member 36 is pressed onthe outer race of aball bearing the inner race of which is pressed on a hub 46 telescoped over the shaft 3th and suitably secured thereto, as by a set screw 48.

The driving clutch element 42 cooperates with a driven clutch element 50 to provide a clutch 52 interposed between the driving member 36 and the drive shaft 30 of the pump 14. The driven clutch element 50, which is also shown as frustoconical, is movable axially into and out of engagement with the driving clutch element 42, there being a splined connection 54 between the driven clutch element and the hub 46 to transmit rotation of the driven clutch element, produced by engagement thereof with the driving clutch element 42, to the hub 46, whereby to drive the pump 14.

Connected to the outer side of the driven clutch element 50 is a cup shaped member 56 containing a spring 58 one end of which is seated against the bottom of the cup shaped member and the other end of which is seated against an annular shoulder 60 on the hub 46. As will be apparent, the spring 58, which is a compression spring, biases the driven clutch element 50 out of engagement with the driving clutch element 42.

Considering the clutch energizing or engaging means 34, it includes diaphragm means 62 responsive to the flow of water through the inlet 18 for biasing the driven clutch element into engagement with the driving clutch element 42 in opposition to the action of the spring 58. The diaphragm means 62 includes a diaphragm 64 closing the open end of a cup shaped diaphragm housing 66, the latter being stationarily mounted on any suitable supporting structure, not shown. The interior of the diaphragm housing 66 is connected to the pump inlet 18, i.e., to the inlet line 22, by a suction line 68 so that the pressure within the diaphragm housing and acting on the inner side of the diaphragm 64 corresponds to the pressure in the inlet 18.

Extending from the exterior of the cup shaped member 56 into the interior of diaphragm housing 66 is a clutch actuating stem 70 having thereon a head 72, a fluid-tight seal between the diaphragm housing and this stem being provided by an O-ring 74. The diaphragm 64 is provided on its outer side with a knob 76 by means of which the diaphragm may be manually moved inwardly into en-- gagement with the head 72 on the stem 7% so as to move the driven clutch element axially into driving engagement with the driving clutch element 42. If desired, the head 72 may incorporate a ball bearing, not shown, the outer race of which is engageable by the diaphragm 64 to prevent rubbing contact between the diaphragm and the head 72.

Considering the operation of the invention, it will be assumed that the water level 78 in the bilge 12 has risen above the lower end 80 of the inlet line 22 and that it is desired to pump out the bilge. In order to do this, it is merely necessary for the operator to press inwardly on the knob 76 to bring the diaphragm into engagement with the head 72 on the actuating stem 70 and to move the actuating stem inwardly until driving engagement between the driven clutch element 50 and the driving clutch element 42 is obtained. Such engagement of the clutch 52 results in driving of the pump 14 to pump water from the bilge 12 through the inlet 18 and into the outlet 20 to be discharged overboard. As soon as the pump 14 starts, the pressure in the inlet line 22 is reduced below atmospheric, and this negative pressure is applied to the inner side of the diaphragm 64 through the suction line 68 to maintain the driven clutch element 50 in driving engagement with the driving clutch element 42 in opposition to the action of the spring 58. Thus, it is necessary for the operator to press inwardly on the knob 76 only long enough for the necessary suction to be developed.

When the water level in the bilge 12 drops to or slightly below the lower end 80 of the inlet line 22, the partial vacuum in the inlet line is immediately broken and the pressure therein rises immediately substantially to atmospheric pressure. When this occurs, the inward, clutch-engaging force applied'to the diaphragm 64 is eliminated, whereupon the spring 58 disengages the clutch 52. Thus, disengagement of the clutch 52 occurs automatically immediately upon breaking of the suction in the inlet line 22 due to lowering of the water level in the bilge 12 to or slightly below the lower end 80 of the inlet line. Consequently, the pump 14 is never emptied so that it is lubricated and cooled at all times by the Water therein and can never run dry with the possibility of consequent damage. Also, since the-pump 14 is never emptied with this construction, any necessity for priming of the pump is avoided in the event that the pump is of the type which requires priming.

While a specific energizable and deenergizable drive means 32 for the pump 14 has been shown, it will be understood that other drive means may be substituted. For example, the drive means may comprise a clutch ofthe type disclosed in the copending application of Warren Doble, one of the applicants herein, Ser. No. 613,016, filed October 1, 1956, issued on November 4, 1958- as Patent Number 2,858,920, and assigned to the assignee of the present invention, it being necessary to add to the clutch disclosed in said copending application a spring, or other means, for disengaging the clutch automatically upon interruption of the clutch-engaging force.

Although we have disclosed an exemplary embodiment of our invention herein, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiment without departing from the spirit of the invention as defined by the claims hereinafter appearing.

We claim as our invention:

1. In a pump control system, the combination of: a pump having an inlet and an outlet; a clutch including a driving element and including a driven element connected to said pump, one of said elements being movable into and out of engagement with the other; movable means for maintaining said movable element in engagement with said other element, said movable means having an area facing in the direction of movement of said movable element into engagement with said other element; means of communication between said inlet and said area for applying the pressure in said inlet to said area, whereby said movable means maintains said movable element in engagement with said other element in response to a pressure less than atmospheric in said inlet; means on said movable means for moving said movable element into engagement with said other element; and spring means engaging said movable element for biasing same out of engagement with said other element.

2. A pump control system as defined in claim 1 wherein said movable means includes a flexible diaphragm engageable with said movable element.

3. A pump control system according to claim 2 wherein said means on said movable means comprises a knob on said diaphragm.

4. A pump control system as defined in claim 3 wherein said movable and other elements of said clutch are rotatable about a common axis and wherein said movable element is movable into and out of engagement with said other element along said axis.

5. In a pump control system, the combination of: a pump having an inlet and an outlet; a clutch including interengageable driving and driven elements one of which is movable into and out of engagement with the other, said driven element being connected to said pump;

movable means connected to said movable elementand. responsive to a pressure less than atmospheric in said inlet for maintaining said movable element in engagement with said other element, said movable means having one area facing in the direction of movement of said movable element into engagement with said other element andhaving another, oppositely facing area'exposed'to the atmosphere; and means of communication between said inlet and said one area for applying the pressure in said inlet to said one area, whereby said movable means maintains said movable element in engagement with said other element in response to a pressure less than atmospheric in said inlet.

6. In a pump control system, the combination of: a pump having an inlet and an outlet; a clutch including interengageable driving and driven elements one of which is movable into and out of engagement with the other, said driven element being connected to said pump; movable means connected to said movable element and responsive to a pressure less than atmospheric in said inlet for maintaining said movable element in engagement with said other element, said movable means having one area facing in the direction of movement of said movable element into engagement with said other element and having another, oppositely facing area exposed to the atmosphere; means of communication between said inlet and said one area for applying the pressure in said inlet to said one area, whereby said movable means maintains said movable element in engage- 6 ment with said other element in response to a pressure less than atmospheric in said inlet; and spring means biasing said movable element out of engagement with said other element.

References Cited in the file of this patent UNITED STATES PATENTS 1,052,034 Bowser Feb. 4, 1913 1,475,994 Havens Dec. 4, 1923 1,949,428 McGee Mar. 6, 1934 2,661,696 Dale Dec. 8, 1953 2,758,547 Wendell et a1 Aug. 14, 1956 2,767,277 Wirth Oct. 16, 1956 FOREIGN PATENTS 90,956 Austria Jan. 25, 1923 121,348 Australia Apr. 11, 1946 OTHER REFERENCES Germany, application No. E7,983 Ia/59b, Feb. 23, 1956. 

